Biocatalytic oxidative cleavage of alkenes using novel metal-dependent aromatic dioxygenases

Abstract

Oxidative cleavage of alkenes can be used to obtain carbonyl compounds, valuable building blocks in various areas, including food, flavor, and the pharmaceutical industry. While this can be done via chemical-synthetic approaches, like ozonolysis, we are interested in milder and safer enzymatic approaches using novel metal-dependent aromatic dioxygenases (ADOs). In the presence of oxygen, these enzymes enable the oxidative cleavage of substrates such as isoeugenol to the corresponding aldehydes. In order to screen numerous substrates in a short time period, we developed a pooling approach using the reported ABAO-assay, a photometric/ fluorometric assay for the detection of the produced aldehydes. The assay is based on the rapid reaction of aldehydes with 2-aminobenzamidoxime (ABAO), forming quinazolines that exhibit UV absorption and fluorescence properties. Using this assay, we want to quickly analyze biotransformations with several pooled substrates by detecting positive/negative photometric/fluorometric responses. In the case of a positive response, GC/HPLC is used to identify the formed aldehydes/the accepted substrate. So far, substrates such as isoeugenol, hydroxyanethole, and 4-vinylguaiacol were found to be successfully converted to the respective aldehydes in a whole-cell system reaction. Among others, especially the MapADO from Moesziomyces aphidis showed promising properties being able to convert 10 mM isoeugenol to vanillin in a whole cell approach within 1 h.